Abstract
The cathode is the most important component of a lithium-ion battery. The olivine structure lithium iron phosphate (LiFePO4) with its numerous appealing features, such as high theoretical capacity, acceptable operating voltage, increased safety, environmental benignity, and low cost, has attracted extensive interest as a potential cathode material for Li-ion batteries. As a precursor, FePO4 can be used to produce LiFePO4 on a large scale with high bulk density, discharge rate, and capacity. This can be realized by controlling the crystal size and morphology of FePO4. The characteristics, structure, and synthesis methods of FePO4 are discussed in this review. The relative merits of these synthetic methods, as well as some suggestions on how to improve them, are also presented.
Similar content being viewed by others
Avoid common mistakes on your manuscript.
Introduction
In recent years, lithium-ion battery has been widely used due to its high voltage and high specific and volumetric energy densities, and easy transportability. Currently, a key factor in the lithium-ion battery is the research of high-voltage cathode materials that has mainly focused on layered transition metal oxides LiMO2 (M = Co, Ni) and spinel structures LiM2O4 (M = Mn, Ni) [1–7]. The widely used LiCoO2-based batteries have problems regarding safety, cost, and environment, which are difficult to overcome. Searching for cheaper, more secure, stable and environmentally friendly cathode materials has become a top priority. LiNiO2, which has a similar structure as LiCoO2, has an advantage with respect to cost and raw materials. However, the difficulties in the synthetic process, the unstable structure, and the poor chemical stability become shortcomings of LiNiO2 to limit its application. Finally, the spinel LiMnO4 has advantages in rich resources of raw materials, low cost, increased safety, environmental friendliness, and simple synthetic process. But further research, development, and application of the synthetic process are hindered by the Jahn–Teller effect in the process of charging and discharging.
In 1997, the Goodenough group [8] first reported that olivine structure lithium iron phosphate (LiFePO4) can display the intercalation/de-intercalation of lithium ions reversibly. Since, LiFePO4 has been considered to be the most promising cathode material for the lithium-ion battery due to its nontoxicity, low cost, and high thermal stability characteristics [9–17]. Unlike other Li electrodes, LiFePO4 exhibits almost theoretical capacity of about 170 mAh g−1 [2], and Li4Ti5O12 also almost shows theoretical capacity (Fig. 1); however, it must be mentioned that the practical capacity depends on C-rate.
The iron sources for preparation of lithium iron phosphate can be divided into trivalent iron sources [18–24] and divalent iron sources [25, 26]. Divalent iron sources are expensive and easily oxidized. Even in an inert atmosphere, it is still difficult to avoid the appearance of Fe3+ impurity. FePO4, as a trivalent iron source, which has a low cost and a high chemical stability, is an ideal material for the synthesis of lithium iron phosphate. LiFePO4 particles can be obtained by controlling the size and morphology of FePO4 with similar characteristics, so as to achieve the target of high bulk density, high discharge rate, and high specific capacity, overcoming the limitation in ionic conductivity of LiFePO4 to a certain extent. In this paper, we review the crystal structure, physical and chemical properties, and charging/discharging mechanism of Li iron phosphate and focus on the aspect of synthesizing iron phosphate as a precursor for lithium-ion batteries.
Crystal structure, and charging/discharging mechanism of iron phosphate
FePO4 [27–30] with amorphous and different crystalline phases has already been synthesized, including heterosite, α-quartz phase, monoclinic system, and orthorhombic system. In this paper, the amorphous state and various crystalline phases of iron phosphate are discussed. However, discussion is limited to phosphate ions in the form of independent PO4 3−, with no expansion to the aggregate state, meaning that the n in (P n O3n + 1)(n + 2)− can only take the value 1, but not 2 or 3. Pressure and temperature can affect the structure of FePO4. At normal pressure, FePO4 exists as α-quartz phase, the same structure as AlPO4. Each phosphorus atom and iron atom are connected to four oxygen atoms. Under a higher pressure, it changes to a tetragonal system similar to CrPO4 with the cell parameters a = 5.227 Å, b = 7.770 Å, and c = 6.332 Å. Then, under a pressure of 2.5 GPa, FePO4 changes to a structure between VCrO4 phase and amorphous state. Recent experimental observations suggest that LiFePO4/FePO4 interfaces are the juxtapositions of the two end members (FePO4 and LiFePO4) instead of solid solutions [31]. However, a solid solution might exist under particular conditions, e.g., at high temperatures [32] or in nanosized particles [33]. FePO4 changes into a trigonal system at 650 °C. When the temperature rises to 705 °C, an α–β phase transition from a P6222 to a P31121 space group occurs [34]. Compared to the tetragonal system of LiFePO4, FeO6 octahedron is replaced by FeO4 tetrahedron in the trigonal system [35] (Fig. 2).
The intercalation/de-intercalation process of lithium ions between FePO4 and LiFePO4 can be expressed as LiFePO4 ⇔ xFePO4 + (1 − x)LiFePO4 + xLi+ + xe− (at 3.45 V/Li) over a large composition range, with a theoretical capacity of 170 mAh g−1. To further study the intercalation process of lithium ions, Padhi et al. [8] proposed a radial model (Fig. 3a). It was suggested that this process is carried out through a two-phase interface with FePO4 and LiFePO4 looking like a coaxial core–shell. During charging, along with lithium-ion inserting, the interface migrates to the particle center and the interfacial area decreases, and when a critical value of area is reached, lithium-ion migration through the interface cannot support the current, and the electrochemical behavior becomes limited by the rate of diffusion (Fig. 3).
Anderson and Thomas [36] proposed a different “Mosaic model.” It is believed that the de-intercalation process of lithium ions can occur over the entire surface area rather than only at the two-phase interface. With the FePO4 phase of the de-lithiation region increasing gradually, the LiFePO4 that remained un-reacted is coated by FePO4 layers in the process, becoming a source of capacity loss. Chen et al. [37] proposed that the FePO4 region and the LiFePO4 region are separated by a dislocation line along the c-axis with anisotropy. In the de-intercalation process of lithium ions, the two-phase interface located at the b–c plane advances along the a-axis horizontally (for details, see Fig. 3b). Laffont et al. [31] proposed that in both the intercalation and de-intercalation processes of lithium ions, the FePO4 region is always in the center of the plane, while the LiFePO4 region can be found close to the edge of area (Fig. 3c). Li-ion migration paths in a unit cell of LiFePO4 are represented in Fig. 4, as summarized by the above three models.
The FePO4 obtained from LiFePO4 with a de-intercalation process of lithium ions, referred to as heterosite structure, belongs to the same Pnma space group with LiFePO4 with a similar structure, exhibiting a small contraction in a and b parameters and a small increase in the c parameter [40] (Table 1).
Synthesis of FePO4 by wet chemical methods
When the synthetic process involves water or is carried out in aqueous solution, the FePO4 obtained often contains crystal water, namely, FePO4·xH2O. Figure 5 shows the thermogravimetry–differential scanning calorimetry (TG-DSC) diagram of FePO4·xH2O obtained by Qian et al. [41]. In the range of 18–500 °C, an obvious endothermic peak in the DSC curve and a well-defined weight loss in the TG curve were observed, corresponding to the loss of crystal water of the precursor. According to the weight loss in this process, the x in FePO4·xH2O can be estimated. The exothermic peaks at 614.46 and 690.63 °C without obvious weight loss can be assigned to structural transformation from amorphous to hexagonal FePO4 and the α–β transition, respectively. Of course, TG-DSC curves vary with different synthetic methods [41, 42] but are generally similar with the previous example.
Xu et al. [40] proposed that Fe2P2O7 appeared at 380 °C and transformed to FePO4 at 460 °C during the heating process. Zhang et al. [43] divided the dehydration process of FePO4·4H2O into a multistep reaction by an iso-conversional rate method and analyzed it by a multivariate nonlinear regression method. They concluded that no branching reaction existed, and the most probable model for the dehydration process is a two-step consecutive reaction with kinetic parameters, such as activation energy and pre-exponential calculated out, for each of the two steps. The most probable kinetic model was estimated with a multivariate nonlinear regression method assuming a two-step consecutive reaction: D4 → Fn. The activation energy E and ln(A/s−1) of D4 were 79.62 kJ mol−1 and 19.35. Those of Fn were 103.04 kJ mol−1 and 25.38 [43].
Boonchom and Danvirutai [44] studied the thermal decomposition kinetics of FePO4·3H2O in air. The FePO4·3H2O decomposed in two steps after 50 °C: the first and second decomposition steps are the loss of one and two molecules of water in crystallization, respectively. The results indicated that the kinetic model, which better describes the second reaction of dehydration for FePO4·3H2O, was the Fn model as a simple nth-order reaction (n = 2.50). The calculated kinetic parameters of the Coats–Redfern method were E a = 77.95 ± 1.18 kJ mol−1 and ln(A/s−1) = 14.26 ± 0.87. Additionally, Boonchom and Puttawong [45] also reported the dehydration reaction of FePO4·2H2O in dynamical air atmosphere. FePO4·2H2O decomposed in one step, and the possible conversion function was based on the three-dimensional diffusion mechanism (D4 model), with the correlated kinetic parameters E a = 65.94 ± 2.83 kJ mol−1 and ln(A/s−1) = 8.32 ± 1.14.
Okawa et al. [46] reported that amorphous FePO4 can be obtained at 350 °C and transformed into a crystalline state at 700 °C, with the specific capacity dropped down to less than a half of the former. This can be attributed to the low activity for FePO4 of the trigonal system and the formation of a glassy phase, Fe3P5O7, covering the surface of FePO4 at 580 °C. This is consistent with the study by Prosini et al. [47]. Chang et al. [48] proposed that a hexagonal layered structure of FePO4 is beneficial to the diffusion of lithium ions to the center of grains, the formation of olivine LiFePO4 along the c-axis, and the carbon coating in the reduction process, as well as the metal ion doping.
Synthetic methods of iron phosphate
FePO4 is not only used as a precursor for LiFePO4, but can also be used as the cathode material directly, however, with a poor cycle performance. In addition, FePO4 has also been used widely as absorbents, catalysts, antirust pigments, and additives. In the electrochemical field, it is imperative that FePO4 contains no undesirable impurities. Wang et al. [49] proposed that the residual moisture in FePO4 can react with Li+ to produce LiOH (Fig. 6a, b), resulting in a higher first capacity and an irreversible degradation in the subsequent cycles. Song et al. [50] proposed that a lower activity for FePO4 sintered at a temperature of 700 °C was caused by a glass phase on the surface (Fig. 6c). Secondly, it requires a high specific surface area and a high bulk density. This can be achieved by producing particles with a small size, a uniform distribution, or a spherical morphology. The electrochemical performance of LiFePO4 is the most important outcome of the synthetic method. Finally, we hope that the synthetic method is simple, convenient, feasible, low cost, fast, environmentally friendly, and easy to achieve industrialization. At present, the synthetic methods of iron phosphate mainly include coordinate precipitation, sonochemical methods, hydrothermal methods, sol–gel methods, homogeneous precipitation, fluoride system methods, surfactant templates, and biologic templates.
Co-precipitation method
The co-precipitation method, also known as liquid phase precipitation method, has a comparable convenient procedure, consumes little energy, requires simple equipment, and can produce particles with small size and uniform distribution. However, this method requires similar precipitation conditions for the raw materials, which may restrict the range of choice for the starting materials. Over the past few years, there have been a number of reports regarding this method. The co-precipitation method can be done via two approaches: the liquid phase oxidation precipitation method and liquid phase non-oxidation precipitation method. The former uses divalent iron source and H2O2 as the oxidant, while the latter uses trivalent iron source, which is cost effective.
Generally, a stoichiometric Fe/P ratio of 1 is used. However, Hu et al. [51] believed that the electrochemical performance can be improved by increasing the H3PO4 proportion. FeSO4 was mainly selected as the iron source for the liquid phase oxidation precipitation method, while Fe(NO3)3 and Fe2(SO4)3 were chosen to be the iron sources for the liquid phase non-oxidation precipitation method. Chang et al. [48] used several kinds of trivalent iron sources and reached the conclusion that a maximum bulk density can be gained by using Fe(NO3)3, which was about double of the bulk density, when Fe2(SO4)3 and FeCl3 were used. H3PO4 or (NH4)2HPO4 is mainly chosen as a phosphorus source. Jiang et al. [52] proposed that a H3PO4/(NH4)2HPO4 ratios of 3:1 can reduce the difficulty of adjusting the pH value.
A too large concentration will result in a large number of lattice defects, while a too low concentration will lead to coarse grain. In addition, the concentration of solution can affect the amount of crystal water, meaning that a higher concentration causes a smaller value for x in FePO4·xH2O. Both the adjustment and the final value of pH value in the synthesis are of great importance. When pH >2.2, a red-brown precipitate of Fe(OH)3 appears, while a too low pH value will result in a incomplete precipitation of Fe3+ and waste. Ma et al. [53] proposed that a low temperature (70 °C or less) was not favorable for the Fe(OH)3 to FePO4·xH2O conversion, while a high temperature was promoting the crystallization of FePO4·xH2O. The whole synthesis process also needed stirring. When the stirring speed increased, the raw materials would react entirely. However, a too high speed can cause a whirlpool in the liquid center, causing uneven mixing away from the center. The FePO4·xH2O amorphous precipitation was collected by filtration, washed with distilled water, dried, grinded, and heated. Chang et al. [48] proposed that the aggregation of FePO4 can be reduced by drying two times (drying under vapor after natural drying), and the bulk density of FePO4 can be increased by nearly 50 % to 2.14 g cm−3 simultaneously. Xia et al. [54] reported that a small amount of Fe2P with a good dispersion after calcination at 800 °C.
In addition, when the flow rate was controlled strictly by a constant flow pump [48], a metering pump [55], or a peristaltic pump [56], the solution was added uniformly rather than mixed directly, and a high-density FePO4 was obtained. Cao et al. [56] reported that the FePO4 particles of large size can get an excellent bulk density (2.03 g cm−3), and the FePO4 particles of middle size delivered a capacity density of 230.4 mAh cm−3 at a rate of 0.1C due to the relatively high bulk density and a lower electrochemical polarization. Zhu et al. [57] reported a facile co-precipitation route through which amorphous iron phosphate particles were synthesized, and the FePO4 obtained featured narrow size distribution, abundant porous structure, and large specific surface.
The homogeneous precipitation method, in which a precipitant is added to achieve a uniform precipitation, can be classified in the liquid phase precipitation method. Carbamide is a commonly used precipitant. Gong et al. [58] reported that the wafer-like FePO4 of hexagonal structure with uniform particle size was obtained by adding a carbamide precipitant and a shape control agent. In the sonochemical method, proposed by Okawa et al. [46], an ultrasonic vibration measure was employed to initiate a series of reactions, mainly generating H2 and H2O2, and achieving oxidation of FeSO4. Although a different name was used, in essence, it was still in the range of the co-precipitation method. This method had the following advantages: no use of oxidation agents, reduction in reaction time, and the ability to control particle size. However, we believe that it may not be suitable for large-scale industrialization due to repeated filtration and washing. The common synthetic process is shown in Fig. 7.
Hydrothermal method
Mal et al. [59] reported that a novel organic–inorganic mesoporous FePO4 had been synthesized by using sodium dodecyl sulfate (SDS) molecules as surfactant, adding FeCl3 and C6H5PO(OH)2 as raw materials under stirring, followed by a heat treatment at 453 K for 15 h in a Teflon-lined stainless steel autoclave (Fig. 8). The hydrothermal method had the following advantages: small size and uniform distribution of particles obtained, simple reaction condition, and completeness of grain growth. The use of autoclave meant that raw materials should be added all at once, that the process was extremely difficult to observe and control, and that industrial production was limited due to the small autoclave container size.
Sol–gel method
Guo [60] reported that the trigonal FePO4 with a particle size of 100 nm was synthesized by using citric acid as ligand after adjusting the pH value and the ligand molar ratio. Lu et al. [61] reported that FePO4 with uniform distribution was synthesized by thermal decomposition of FeOPO(OC6H4COOH)2·0.5H2O precursor prepared from a HOPO(OC6H4COOH)2 ligand dissolved in distilled water (70 %) and ethanol (30 %) with the addition of Fe(NO3)3 drop-wise under continuous stirring (Fig. 9). It was suggested that the existence of a little residual carbon after thermal decomposition can improve the conductivity of the cathode material. The advantages of the sol–gel method were low temperature and high uniformity. But a large number of micropores in the gel may cause contraction during the drying process. The best discharge capacity of the synthesized samples around 380 °C was 146 mAh g−1.
Fluoride system method
Guo [60] reported that the hexagonal mesoporous FePO4 with a particle size of 2.6 nm was synthesized by adding HF as mineralizer and sodium dodecyl sulfate as surfactant into FePO4 (prepared by mixing Na2HPO4 with Fe(NO3)3 suspension and reacting at 60 °C for 2.5 h) (Fig. 10). However, the removal of impurities was cumbersome. It was proposed that neither NaF nor NH4F can work well, while HF with a low dissociation degree could form a hydrogen bonding between [FeHPO4]+–F− ion pairs. Also, the F− anions had an effect on the electrostatic interaction between ion pairs and anionic surfactant micelles. They also enhanced the formation of the hexagonal mesostructured phase.
Surfactant template method
In this method, mesoporous materials are synthesized under the guide function of templates. Zhu et al. [62] reported that highly ordered hexagonal mesoporous FePO4 was synthesized by adding cetyltrimethylammonium chloride (CTMACl) into Fe2(SO4)3 and H3PO4 raw materials. However, it was pointed out that only 50 % of CTMACl can be removed effectively. Similarly, Shi et al. [63] took a surfactant (EO20–PO20–EO20, Plurinic P123) as the template. They proposed that a little residual carbon would be left in FePO4 after heating and a collapse of the mesoporous structure would happen in the temperature range of 500–600 °C. The mesoporous FePO4 delivered enhanced specific capacity of 160 mAh g−1 at the first discharge process and 135 mAh g−1 in the following cycles at 0.1C rate. Wang et al. [64] reported that cetyltrimethylammonium bromide (CTAB) was also suitable to be a template (Fig. 11). The LiFePO4/C nanoparticles lithiated from the obtained FePO4·2H2O nanoplates delivered discharge capacities of more than 150, 120, 110, 100, and 75 mAh g−1 at rates of 5C, 10C, 15C, 20C, and 30C, respectively.
Biologic template method
In the so-called biologic template method, organisms provided nucleation sites to regulate the grain growth. Zhou et al. [65] reported that iron phosphate nanopowders with flake morphology had been synthesized with yeast cells as a biologic template. In the synthetic process, the biologic template adsorbed Fe3+ cations firstly, which led to the formation of FePO4. They pointed that the organisms could be removed completely after heating at 500 °C and only little conductive carbon was left. Similarly, Cao and Li [66] reported that iron phosphate hollow microspheres were obtained with pollen grains as biologic template (Fig. 12).
Other synthetic methods
Chen et al. [67] reported that crystalline FePO4 had been synthesized through a reaction between iron powder, H3PO4, and NH4H2PO4 in aqueous solution and mixed with conductive agent after grinding. This synthetic method was simple and low cost; however, the electrochemical performance was poor. Wu et al. [68] prepared nano FePO4·xH2O powders by controlled crystallization method, using Fe(III) compound as the iron source. Then, the olivine nano LiFePO4/C composites were obtained through carbothermal reduction process at different temperatures. The results show that the nano LiFePO4/C composite calcined at 700 °C for 10 h has fine particle sizes of about 40–100 nm. The nano LiFePO4/C composite cathode material can deliver an initial discharge capacity of 156.5, 134.9, 105.8, 90.3, and 80.9 mAh g−1 in the voltage range of 2.5–4.2 V, at a rate of 0.1C, 1C, 5C, 10C, and 15C, respectively, which exhibits good rate performance.
Okada et al. [35] reported that an increase of more than 35 % in specific capacity can be obtained by mixing P2O5 with Fe, ball milling with water for 24 h, and subsequent heating and ball milling without water for 24 h. Delacourt et al. [69] reported that several different hydrated iron phosphates were prepared under refluxing conditions. The low temperature solid phase method [70] took high energy consumption in the synthesis process, and the uniformity of particle size distribution was relatively poor. Qian et al. [41] reported that amorphous FePO4 had been synthesized by an electrochemical synthetic method with H3PO4 as the electrolyte, iron as the anode, and H2O2 as the oxidant. This method may be a new direction to prepare FePO4.
Conclusion and prospection
In this paper, the structure, properties, and various synthetic methods of iron phosphate were discussed, with a focus on the synthetic methods. One common issue that needs to be addressed is that although some researchers had synthesized FePO4 of a large surface area or small particle size, the electrochemical performances of the ultimate product LiFePO4 were still unknown. On one hand, to obtain an appropriate FePO4 precursor, researchers should continue to increase bulk density, reduce cost, and optimize details to adapt to industrialization. On the other hand, the coordination between synthetic methods for FePO4 precursor and the subsequent lithium insertion operation should be taken into consideration. In general, the method to prepare LiFePO4 was mixing the FePO4 precursor with a carbon source and a lithium source in a tube furnace by carbothermal reduction method, which inevitably led to a reduction of bulk density and an enlargement of particle size. At present, some researchers also take a rheological phase method [71] as well as other methods.
References
Xiong LL, Xu YL, Tao T et al (2012) Synthesis and electrochemical characterization of multi-cations doped spinel LiMn2O4 used for lithium ion batteries. J Power Sources 199:214–219
Fergus JW (2010) Recent developments in cathode materials for lithium ion batteries. J Power Sources 195(4):939–954
Seung SH, Chang GC, Kyu-Sung P (2011) Stabilizing LiCoO2 electrode with an overlayer of LiNi0.5Mn1.5O4 by using a Gravure printing method. Electrochem Commun 13(3):279–283
Arumugam D, Kalaignan GP (2011) Electrochemical characterizations of surface modified LiMn2O4 cathode materials for high temperature lithium battery applications. Thin Solid Films 520:338–343
Grigorova E, Mandzhukova TS, Khristov M et al (2011) Soft mechanochemically assisted synthesis of nano-sized LiCoO2 with a layered structure. J Mater Sci 46:7106–7113
Zhao CH, Kang WP, Zhao SQ et al (2011) Hydrazine–hydrothermal synthesis of pure-phase O-LiMnO2 for lithium-ion battery application. Micro Nano Lett 6(10):820–822
Shan YX, Wang QC, Meng QZ (2010) Research progress on lithium iron phosphate as lithium ion battery cathode material. Sci Technol Chem Ind 18(3):80–82
Padhi AK, Nanjundaswamy KS, Goodenough JB (1997) Phospho-olivines as positive-electrode materials for rechargable lithium batteries. J Electrochem Soc 144:1188–1190
Zhang W-J (2011) Structure and performance of LiFePO4 cathode materials: a review. J Power Sources 196:2962–2970
Zhao Z-w, Si X-f, Liang X-x et al (2013) Electrochemical behavior of Li+, Mg2+, Na+ and K+ in LiFePO4/FePO4 structures. Trans Nonferrous Metals Soc China 23:1157–1164
Zhang Y, Huo Q-y, Du P-p et al (2012) Advances in new cathode material LiFePO4 for lithium-ion batteries. Synth Met 162:1315–1326
Purwadi A, Dozeno J, Heryana N (2013) Testing performance of 10 kW BLDC motor and LiFePO4 battery on ITB-1 electric car prototype. Procedia Technol 11:1074–1082
Yoon M-S, Islam M, Ur S-C (2013) The role of impurities on electrochemical properties of LiFePO4 cathode material. Ceram Int 39:S647–S651
He L, Liu X, Zhao Z (2013) Non-isothermal kinetics study on synthesis of LiFePO4 via carbothermal reduction method. Thermochim Acta 566:298–304
Jung J, Cho M, Zhou M (2013) Ab initio study of the fracture energy of LiFePO4/FePO4 interfaces. J Power Sources 243:706–714
Vediappan K, Guerfi A, Gariépy V et al (2014) Stirring effect in hydrothermal synthesis of nano C-LiFePO4. J Power Sources 266:99–106
Ren Y, Bruce PG (2012) Mesoporous LiFePO4 as a cathode material for rechargeable lithium ion batteries. Electrochem Commun 17:60–62
Lv Y-J, Long Y-F, Su J et al (2014) Synthesis of bowl-like mesoporous LiFePO4/C composites as cathode materials for lithium ion batteries. Electrochim Acta 119:155–163
Wu Y-F, Liu Y-N, Guo S-W (2014) Hierarchical carbon-coated LiFePO4 nano-grain microspheres with high electrochemical performance as cathode for lithium ion batteries. J Power Sources 256:336–344
Zhao Z, Si X, Liu X et al (2013) Li extraction from high Mg/Li ratio brine with LiFePO4/FePO4 as electrode materials. Hydrometallurgy 133:75–83
Gim J, Song J, Nguyen D et al (2014) A two-step solid state synthesis of LiFePO4/C cathode with varying carbon contents for Li-ion batteries. Ceram Int 40:1561–1567
Tan L, Zhang L, Sun Q et al (2013) Capacity loss induced by lithium deposition at graphite anode for LiFePO4/graphite cell cycling at different temperatures. Electrochim Acta 111:802–808
Zhang Y, Wu L, Zhao J et al (2014) A facile precursor-separated method to synthesize nano-crystalline LiFePO4/C cathode materials. J Electroanal Chem 719:1–6
Xing Y, He Y-B, Li B, Chu X, Chen H, Ma J, Du H, Kang F (2013) LiFePO4/C composite with 3D carbon conductive network for rechargeable lithium ion batteries. Electrochim Acta 109:512–518
Liu X, Chen X, Zhao Z, Liang X (2014) Effect of Na+ on Li extraction from brine using LiFePO4/FePO4 electrodes. Hydrometallurgy 146:24–28
Liu S, Wang H (2014) WO2 modified LiFePO4/C cathode materials with improved electrochemical performance synthesized by in-situ synthesis method. Mater Lett 122:151–154
Mi CH, Cao GS, Zhao XP (2005) One-step solid-state synthesis and high-temperature electrochemical performance of carbon coated LiFePO4 cathode. Chin J Inorg Chem 4:556–560
Kinomura N, Shimada M, Koizumi M et al (1976) Synthesis of a high pressure phase of FePO4. Mater Res Bull 11(5):457–460
Ait-Salah A, Dodd J, Mauger A, Yazami R, Gendron F, Julien CM (2006) Structural and magnetic properties of LiFePO4 and lithium extraction effects. Z Anorg Allg Chem 632:1598–1605
Scaccia S, Carewska M, Prosini PP (2004) Thermoanalytical study of iron(III) phosphate obtained by homogeneous precipitation from different media. Thermochim Acta 413:81–86
Laffont L, Delacourt C, Gibot P, Wu MY, Kooyman P et al (2006) Study of the LiFePO4/FePO4 two-phase system by high-resolution electron energy loss spectroscopy. Chem Mater 18:5520–5529
Delacourt C, Rodríguez-Carvajal J, Schmitt B, Tarascon JM, Masquelier C (2005) Crystal chemistry of the olivine-type LixFePO4 system (0 ≤ x ≤ 1) between 25 and 370 °C. Solid State Sci 7:1506–1516
Meethong N, Huang HYS, Carter WC, Chiang YM (2007) Size-dependent lithium miscibility gap in nanoscale Li1-xFePO4. Electrochem Solid-State Lett 10:A134–A138
Aliounae N, Badeche T, Gagou Y et al (2000) Synthesis and phase transitions of iron phosphate. Ferroelectrics 241(1):255–262
Okadaa S, Yamamotoa T, Okazaki Y et al (2005) Cathode properties of amorphous and crystalline FePO4. J Power Sources 146:570–574
Anderson AS, Thomas JO (2010) The source of first cycle capacity loss in LiFePO4. J Power Sources 97–98:498–502
Chen G, Song X, Richardson TJ (2006) Electron microscopy study of the LiFePO4 to FePO4 phase transition. Electrochem Solid-State Lett 9:A295–A298
Ming T, Craig WC, Yet-Ming C (2010) Electrochemically driven phase transitions in insertion electrodes for lithium-ion batteries: examples in lithium metal phosphate olivines. Annu Rev Mater Res 40:501–529
Saiful IM, Daniel JD, Craig AJF et al (2005) Atomic-scale investigation of defects, dopants, and lithium transport in the LiFePO4 olivine-type battery material. Chem Mater 17:5085–5092
Xu YB, Lu YJ, Yin P et al (2008) A versatile method for preparing FePO4 and study on its electrode performance in lithium ion batteries. J Mater Process Technol 204:513–519
Qian LC, Xia Y, Zhang WK et al (2012) Electrochemical synthesis of mesoporous FePO4 nanoparticles for fabricating high performance LiFePO4/C cathode materials. Microporous Mesoporous Mater 152:128–133
Wang ZX, Wu L, Li XH et al (2008) Preparation of precursor and performance of LiFePO4. J Funct Mater 4(39):614–617
Zhang MF, Hong JH, Yuan LJ et al (2009) Kinetics of dehydration of FePO4·4H2O in air. Chin J Inorg Chem 25(6):1022–1025
Boonchom B, Danvirutai C (2007) Thermal decomposition kinetics of FePO4·3H2O precursor to synthetize spherical nanoparticles FePO4. Ind Eng Chem Res 46:9071–9076
Boonchom B, Puttawong S (2010) Thermodynamics and kinetics of the dehydration reaction of FePO4·2H2O. Physica B 405:2350–2355
Okawa H, Yabuki J, Kawamura Y et al (2008) Synthesis of FePO4 cathode material for lithium ion batteries by a sonochemical method. Mater Res Bull 43:1203–1208
Prosini PP, LiSi M, Scaccia S et al (2002) Synthesis and characterization of amorphous hydrated FePO4 and its electrode performance in lithium batteries. J Electrochem Soc A149:297–300
Chang JY, Zhang JY, Feng T (2007) Preparation and performance test of FePO4 precursor for high density LiFePO4. J Yellow River Conservancy Tech Inst 23(3):51–54
Wang X, Yang XH, Zheng HG et al (2005) Synthesis and electrochemical performance of amorphous hydrated iron phosphate nanoparticles. J Cryst Growth 274:214–217
Song YN, Yang SF, Zavalij PY et al (2002) Temperature-dependent properties of FePO4 cathode materials. Mater Res Bull 37:1249–1257
Hu GR, Zhou YL, Peng ZD et al (2007) Preparation and performance of FePO4 precursor for LiFePO4. Battery Bimonthly 37(5):339–341
Jiang DP, Zhang XJ, Lu SG et al (2011) Research on process of preparation and performance of iron phosphate as precusor of lithium iron phosphate. Rare Metals 30:52–54
Ma GC, Ting SW, Li Q et al (1993) Studies on synthesis and properties of iron(III) phosphate. J Hebei Univ (Sci Technol) 13(4):54–57
Xia JP, Deng XC, Wang LL (2010) Influence of synthesis time on the properties of LiFePO4/C composites with self-produced FePO4 as iron source. Chin Battery Ind 15(6):354–358
Lei M, Ying JR, Jiang CY et al (2006) Preparation and characteristic of high-density spherical LiFePO4. Chin J Power Sources 30(1):11–13
Cao Y, Wang ZG, Yang H (2011) Synthesis and electrochemical properties of spherical LiFePO4 with various particle sizes as cathode material for lithium ion batteries. J Funct Mater 3(42):448–451
Zhu YM, Tang SZ, Shi HH et al (2014) Synthesis of FePO4.xH2O for fabricating submicrometer structured LiFePO4/C by a co-precipitation method. Ceram Int 40:2685–2690
Gong FZ, Yi JH, Zhou LY et al (2009) Preparation of two kinds of FePO4 powders with different morphologies and electrochemical properties of LiFePO4. J Guangxi Univ Nat Sci Ed 34(6):731–735
Mal K, Bhaumik A, Matsukata M et al (2006) Syntheses of mesoporous hybrid iron oxophenyl phosphate, iron oxophosphate, and sulfonated oxophenyl phosphate. Ind Eng Chem Res 45:7748–7751
Guo XF (2000) Preparation, characterization and catalytic properties of nanoparticles and mesostructured materials. Nanjing University, Nanjing
Lu YJ, Xu YB, Yang RD et al (2007) A versatile method for preparing FePO4 as a promising electrode material for rechargeable lithium batteries. J Lanzhou Univ (Nat Sci) 43(4):144–146
Zhu SM, Zhou HS, Hibino M et al (2004) Synthesis of hexagonal mesostructured FePO4 using cationic surfactant as the template. Chem Lett 33(6):774–775
Shi ZC, Attia A, Ye WL et al (2008) Synthesis, characterization and electrochemical performance of mesoporous FePO4 as cathode material for rechargeable lithium batteries. Electrochim Acta 53:2665–2673
Wang M, Xue YH, Zhang KL et al (2011) Synthesis of FePO4·2H2O nanoplates and their usage for fabricating superior high-rate performance LiFePO4. Electrochim Acta 56:4294–4298
Zhou WJ, He W, Zhang XD et al (2009) Biosynthesis of iron phosphate nanopowders. Powder Technol 194:106–108
Cao F, Li DX (2010) Biotemplate synthesis of monodispersed iron phosphate hollow microspheres. Bioinspir Biomim 5:1748–3182
Chen YK, Okada S, Yamaki J-i (2002) Preparation of ferri phosphate and its application to lithium battery. J Huaqiao Univ (Nat Sci) 23(4):407–411
Wu YL, Pu WH, Jiang CY et al (2012) Synthesis of nano FePO4 and electrochemical characterization of composite cathode material LiFePO4/C. J Inorg Mater 27(4):422–426
Delacourt C, Wurm C, Morcrette M et al (2003) Synthesis and thermal behavior of crystalline hydrated iron(III) phosphates of interest as positive electrodes in Li batteries. Chem Mater 15(26):5051–5058
Fan W (2009) Synthesis and electrochemical characterization of FePO4 by a solid state reaction at low-heating temperature. Nanjing Normal University, Nanjing
Wang LN, Zhang ZG, Zhang KL (2007) A simple, cheap soft synthesis routine for LiFePO4 using iron(III) raw material. J Power Sources 167:200–205
Acknowledgments
The financial support of China Postdoctoral Science Foundation (2012M520717) and Natural Scientific Research Innovation Foundation in Harbin Institute of Technology (HIT.NSRIF.2011099) is gratefully acknowledged.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Zhu, Ym., Ruan, Zw., Tang, Sz. et al. Research status in preparation of FePO4: a review. Ionics 20, 1501–1510 (2014). https://doi.org/10.1007/s11581-014-1241-x
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11581-014-1241-x